The present invention in general relates to the mounting of electrical components on and within a substrate. More particularly, the invention relates to the mounting of such components on and within a printed circuit board (PCB). Still more specifically, the invention pertains to mounting such components having male pins or the like within a receiving contact or socket positioned within a substrate (e.g., a PCB structure) and adapted for being surface mounted on a separate PCB or the like.
Electronic circuits have become so miniaturized to meet many of today""s design requirements that the connector size relatively dwarfs the circuit it is connected to. The two major ways that electrical components (e.g., modules, resistors, capacitors, etc.) are attached to PCBs are to PCBs that have accommodating holes therein, and PCBs without such holes. Many PCB designs may include a combination of both. Such holes typically extend entirely through the PCB and are thus called xe2x80x9cthrough holesxe2x80x9d while others may only reach a predetermined depth within the PCB, and are called xe2x80x9cblind holesxe2x80x9d or xe2x80x9cblind viasxe2x80x9d. An example of a PCB having both such holes is defined in U.S. Pat. No. 5,451,721 (Tsukada et al). In boards with holes (typically produced by drilling or punching), a component is inserted into the hole in the board. Such components typically include a pin or similar male projection (e.g., a resistor may include two opposing end wires of sufficient rigidity to enable direct hole insertion) and the component may be held in place by an interference fit, clinch, or a spring formed on a component pin (or leg). After all components are so positioned, these are subsequently soldered to the PCB. Various types of contacts (connectors) that can be positioned within a PCB or suitable insulative housing for mating with an also internally positioned pin or the like protruding contact are defined in the following U.S. Patents:
U.S. Pat. No. 3,862,792xe2x80x94Jayne
U.S. Pat. No. 3,915,537xe2x80x94Harris et al
U.S. Pat. No. 4,906,198xe2x80x94Cosimano et al
U.S. Pat. No. 4,927,387xe2x80x94Eckler et al
U.S. Pat. No. 5,162,003xe2x80x94Johnson et al
U.S. Pat. No. 5,167,544xe2x80x94Brinkman et al
U.S. Pat. No. 5,189,261xe2x80x94Alexander et al
The use of such pins and mating internal board contacts is referred to in the industry as pin-in-hole (PIH) technology.
In PCBs without holes, the components are typically surface mounted. In this case, the pads on the receiving board are printed with solder (usually paste) and the components are placed on these solder pads. The solder is then reflowed. The great advantage in surface mount is that there is a potential real estate board savings of up to 70% of the area of the board. The surface positioning of such components on PCBs is referred to in the industry as surface mount technology (SMT).
Mounting components on the surface of a PCB usually involves the application of a highly viscous solder alloy (typically, by silk-screening methodology) to various solder joint locations on the flat surface of the PCB. The solder paste will retain the loaded components in their correct position up through the soldering process. Reflow solderingxe2x80x94where the PCB carrying the loaded components and the solder paste is baked in an elevated temperature chamberxe2x80x94is achieved when the joint temperatures reach a predetermined temperature, usually about 250xc2x0 C. The solder paste liquifies and coats the solder contacts of the respective parts and the PCB""s solder pad. Thereafter, cooling of the assembly causes solidification of the solder, and electrical and mechanical bonding of the surface mounted component to the PCB is completed.
Examples of assemblies in which an electrical component is surface mounted on a PCB or the like substrate are defined in the following U.S. Patents:
U.S. Pat. No. 5,280,414xe2x80x94Davis et al
U.S. Pat. No. 5,561,322xe2x80x94Wilson
U.S. Pat. No. 5,633,533xe2x80x94Andros et al
U.S. Pat. No. 5,728,606xe2x80x94Laine et al
U.S. Pat. No. 5,773,884xe2x80x94Andros et al
U.S. Pat. No. 5,798,563xe2x80x94Feilchenfeld et al
An example of an assembly which defines the use of pins to mount a component into a PCB while also defining the use of solder to mount a component (here, a chip) onto a substrate is defined in U.S. Pat. No. 5,847,929 (Bernier et al).
For some PIH mounting (soldering) applications, so called xe2x80x9cMiniature One-Piece Contactsxe2x80x9d are on the market. An example is shown in FIG. 2. These contacts were developed from earlier xe2x80x9cTwo Piece PGA Contactsxe2x80x9d, designed for PGA (pin grid array) sockets with a small contact distance, e.g., smaller than 1.27 mm (50 mil). Such xe2x80x9cMiniature One-Piece Contactsxe2x80x9d are intended for the realization of a 1 mm high-terminal contact field and have a greater lateral isolation distance to the pluggable partner than their predecessors. These contacts are therefore more forgiving to mechanical tolerances. Said xe2x80x9cMiniature One-Piece Contactsxe2x80x9d (as seen in FIG. 2) can be arranged in a two-dimensional array held within an insulative housing. However, limits are set to the direct application of xe2x80x9cMiniature One-Piece Contactsxe2x80x9d in PIH implementation, so that using SMT is usually preferred. In addition, SMT implementation is an alternative as a detachable connecting element for existing SMT modules (solderball/soldercolumn). By the term xe2x80x9ccontact memberxe2x80x9d as used herein is meant to define an electrically conductive article adapted for being electrically connected to two separate electrical conductors such as PCB pads, male conductive pins, internally plated PCB through holes or vias, etc. When such a contact member is combined with a pinned element (e.g., the pin is inserted therein), the term xe2x80x9ccontact assemblyxe2x80x9d is used. Such an assembly, as explained hereinbelow, may be adapted for being positioned within an insulative housing, substrate or PCB and in turn directly electrically coupled to a second housing, substrate or PCB.
Due to the increasing demand for miniaturization in products such as those mentioned above, there are limits (because of hole, bore and clearance diameters and tolerances) when using even more recent plated-through-hole (PTH) technology. Plated through holes are understood to be through holes in the PCB with appropriate internal plating (e.g., copper) for coupling to internally positioned components and/or internal conductive planes. One limiting factor here is, among other things, the distance useable for the conductors between two adjacent PTHs, which distance may also be defined as the channel width. In the case of multilayer-PCBs (boards having several conductor and insulative layers stacked on one another), useable channel width is additionally narrowed due to registration tolerances when laminating the different planar conductive and insulative layers.
Although contacts for PIH and for SMT utilization having separate sleeve and contact springs are known including contacts of one-piece construction, it is believed that a new and unique contact member and assembly adapted especially for surface mount use while also providing pin accommodation would constitute an advancement in the art.
It is, therefore, an object of the present invention to provide a new and improved contact member for use in PCB surface mounting applications.
It is a further object of the invention to provide such a contact member which, when combined with another pinned contact member, will include both sleeve and spring features. As stated, such a combination will be referred to herein as a contact assembly.
It is still a further object of the present invention to provide such a contact member and assembly which is of relatively simple construction and which can be readily produced using mass production, thus resulting in a reduced cost final product.
According to one aspect of the invention, there is provided a contact assembly comprising a first contact member including a sleeve portion and a male pin portion, the first contact member adapted for being positioned within a dielectric substrate or housing, and a second contact member fixedly secured to the male pin portion of the first contact member and including a substantially flat end surface adapted for being soldered onto an electrical conductor.
According to another aspect of the invention, there is provided a connector assembly comprising an insulative substrate or housing, a plurality of contact assemblies positioned within the insulative substrate or housing, each of the contact assemblies including a first contact member securedly positioned within the insulative substrate or housing and including a sleeve portion and a male pin portion, and a second contact member fixedly secured to the male pin portion of the first contact member and including a substantially flat end surface adapted for being soldered onto an electrical conductor.
According to yet another aspect of the invention, there is provided an electronic assembly comprising a first substrate, a connector assembly positioned on the first substrate and electrically coupled thereto, the connector assembly including an insulative second substrate or housing and a plurality of contact assemblies positioned within the second substrate or housing. Each of the contact assemblies includes a first contact member securedly positioned within the insulative substrate or housing and including a sleeve portion and a male pin portion, and a second contact member fixedly secured to the male pin portion of the first contact member and including a substantially flat end surface adapted for being soldered onto an electrical conductor of the first substrate.
According to still another aspect of the invention, there is provided a method for making a contact assembly comprising the steps of providing a first contact member including a sleeve portion and a male pin portion, providing a second contact member including a substantially flat end surface, and soldering the second contact member onto the male pin portion of the first contact member.